Seh. GOlNrGYLOSPERlMKJ;. ( 139 ) Fam. CERAMIACE^E. 



Plate CXV. 

 GRIFFITHSIA SETACEA.— ^^. 



Gen. CnAR. — " Frond rose-red, filamentous; filaments jointed tliroughout, mostly dicho- 

 tomous; ramuli single-tubed ; dissepiments hyaline." Fructification of two kinds, 

 on distinct plants : 1. Favellce, surrounded by an involucre ; 2. Tetraspores, 

 attached to whorled "involucral ramuli." Name in honour of Mrs. Griffiths, well 

 known for her numerous and valuable discoveries among British Algte. 



Grifpithsia setacea. — Fronds filamentous, setaceous, rather rigid and 

 straight, dichotomously branched ; branches erect ; articidations cylin- 

 drical, those of the main stems five to six times longer than broad ; 

 fructification lateral, on jointed stalks. 



Griffithsia setacea. — Ag. Syn. p. 28; Ag. Syst. p. 144; Ag. Sp. Alg. vol. ii. 

 p. 129 ; Grev. Fl. Edin. p. 312 ; Hook. Br. Fl. vol. ii. p. 338; Wyatt, 

 Alg, Danm. No. 137 ; Eyidl. 3rd Suppl. p. 35 ; Kiltz. Phyc. Gen. 

 p. 373 ; Hooh. fit. Fl. Ant. vol. i. p. 191 ; JIarv. in MacTc. Fl. Hih. 

 part 3, p. 212 ; Harv. P. B. plate 184 ; Harv. Man. p. 169 ; Earv. 

 Syn. p. 141 ; Atlas, plate 55, fig. 253 ; /. G. Agardh, Sp. Gen. Alg. 

 vol. ii. p. 84. 

 Conferva setacea. — -ElUs, Phil. Trans, vol. Ivii. t. 18 f, e ; Turn. Linn. Trans. 

 vol. vii. p. 107 ; Buds. Fl. Angl. p. 599 ; With. PL vol. iv. p. 137 ; 

 E. Bot. t. 1689 ; Dillw. Conf. t. 82 ; Both, Cat. Bot. vol. iii. p. 278. 

 Hab. — In shady rock -pools, generally near low -water mark. Annual ? Spring, 

 summer, and early autumn. Common. 



Geogr. Dist. — Atlantic shores of Europe and America ; Southern Ocean, 



Description. — Root, a mass of ci-eeping fibres. Fronds much tufted, 

 filamentous, setaceous, two to six or eight inches long, as thick as fine 

 hair, much branched in a more or less regularly dichotomous manner ; 

 branches sometimes opposite, very erect, with acute axils, cylindrical 

 below, setaceous upwards, the apices acute, frequently much matted 

 near the base, and entangled by small lateral root - like processes. 

 Articiilations cylindrical, those of the main stems five to six times as 

 long as broad, shorter upwards, all cylindrical, apical one conical acute. 

 Substance rather firm and rigid when fresh, but soon becomes flaccid 

 on exposure to the air or in fresh water, and adheres, but not very 

 strongly, to paper. Colour, a fine transparent crimson, rapidly dis- 

 charged in fresh water " with a crackling noise," from the rupture of the 

 membranous walls of the tubes. Favellse produced on the inner faces of 

 short, incurved involucral ramuli, oval, mostly in pairs. Tetraspores 



